Intimate partner enters the shared fantasy in order to facilitate the narcissistic solution to the schizoid state: serve as fetishized womb (mother) and affirm the reality and veracity of the False Self. She is misperceived as external object, when actually the narcissist internalized her to guarantee her functioning and prevent abandonment.
Narcissist internalizes all external objects. So Madonna Whore complex is not a splitting defense directed at external objects (women), but at an internal one: the self is split to all body and all mental (Guntrip).
Abandonment is equivalent of birth: being forced back into the world and external object relations. Hence the extreme anxiety, decompensation, acting out, and protector self-state (secondary psychopathy).
Ego evolves - moulded and jumpstarted - via external object relations. Derives strength and sense of reality.
Safety (fear flight reaction) via not being: absence, emptiness, ironically ego death.
Narcissism is an attempt to avoid this solution via grandiose fantasies of invulnerability, omnipotence, and omniscience.
Their locus is the False Self, a construct which represents a compromise: external object relations one step removed and with a decoy - and schizoid inner absence (being unborn, egoless) where a real core should have been.
Narcissism is fetishism: fantasy defenses against the schizoid state (death).
When they fail (mortification), narcissist becomes schizoid.
Then he resurrects (born again) into renewed narcissism.
Like narcissism, Paranoia and depression are also defenses against schizoid state: if external object relations are too threatening, next best is internal object relations (rather than schizoid no object relations and no ego).
Internal objects can be persecutory (eg inner critic). The narcissist, though, experiences them as external (paranoia) and, in an attempt to control his aggression, becomes depressed (substitute for guilt in healthy people).
Schizoid chooses the safety of withdrawal-avoidance from reality and external objects to internal objects (esp. mother) via merger/fusion/assimilation (womb).
Narcissist chooses the pleasure of approach-mastery of external objects via grandiosity and exploitive entitlement (incest).
Both are regressive-infantile.
Codependency and Borderline are composites: merger and fusion are both safe and pleasurable. This is accomplished via pseudopsychosis: externalizing internal objects (such as mother's womb).
Find and Buy MOST of my BOOKS and eBOOKS in my Amazon Store: https://www.amazon.com/stores/page/60F8EC8A-5812-4007-9F2C-DFA02EA713B3